1. Technical Field
This disclosure relates generally to manufacturing processes for razor blades, and more specifically to methods of imparting a weakened area to razor blades.
2. Background
Many modern safety razors include a disposable razor cartridge adapted to be selectively connected to a reusable handle by connecting structure therebetween. The cartridge includes a housing having at least one razor blade with a sharpened cutting edge disposed therein. Other modern safety razors include a razor cartridge permanently connected to the handle that can be disposed of as a single unit.
Razor blades are typically made from a continuous strip of stock material that is hardened and subsequently sharpened while the strip travels along a processing line. The strip is then divided into discrete blade length sections used in manufacture of individual cartridges.
In some applications, blades are supported on respective bent supports that are mounted in the cartridge housing. To enable the supported blades to move up and down within the housing during shaving and/or to provide efficient rinsing of shaving debris from between adjacent supported blades it is desirous that the blades have a small width dimension defined perpendicular to the cutting edge. In U.S. Pat. No. 7,131,202 the desirability of a razor blade having a width dimension less than 0.85 mm is disclosed.
In U.S. Pat. No. 6,629,475, a razor blade having a removable portion is provided to facilitate efficient handling, processing and attachment of the razor blade to its support. The removable portion and razor blade are connected at a weakened portion provided to allow the removable portion to be easily removed after the razor blade has been attached to its support. The '475 patent discloses a method of using rolling apparatus to provide the weakened portion. The deforming process is performed to continuous strip material before the strip is cut into discrete blade sections and according to FIG. 5 therein at least before the cutting edge is provided.
In U.S. Pat. No. 7,531,052, apparatus is disclosed to provide a weakened portion for a razor blade using thermal energy, preferably by a laser, to provide an elongated groove in one side of a continuous strip of material. The thermal grooving process is performed to the strip while it is in an as-provided annealed state, i.e. prior to any hardening process and subsequent sharpening process.
In European Patent EP 2203282 B1 a bending process performed to stock material causes inter-granular cleavage. Exposed grain boundaries are oxidized during a subsequent hardening process.
In the three documents mentioned immediately preceding, the respective processes to provide a weakened area are performed to material in continuous strip form and prior to any sharpening process.